1. Field of the Invention
The present invention relates to a presence information provision method for providing mainly data communication service to a user and providing presence service to the user in order to provide the data communication service with improved effectiveness in a communication system having a plurality of communication nodes such as a communication terminal used by the user. The invention also relates to a presence information provision system for performing the method.
2. Description of the Related Art
The presence service is defined as informing one user of another user's presence information that is indicative of presence such as the another user's contract status, availability for communications, and whether he or she will respond to a message (see Non Patent Document 1). For example, a presence service by a communication system for providing telephone call services is configured to inform one user of another user's availability for call connections or whether he or she will respond to an incoming call.
FIG. 1 is a view illustrating how to exchange presence information in a conventional presence service.
In FIG. 1, it is assumed that a user A uses a communication terminal A (node A), a user B uses a communication terminal B (node B), and a presence server is available for providing control to presence services.
Here, suppose that the user A is going to inform another user of the presence information that the user A will respond to the incoming call from the another user. In this case, first, the node A transmits a PUBLISH message with the presence information to the presence server. The presence server receives the transmitted presence information and then associates it with the user A to retain it therein.
Now, suppose that the user B desires a call to be connected to the user A. In this case, the node B transmits a SUBSCRIBE message directed to the node A to the presence server prior to making a call to the node A. In response to this, the presence server transmits the presence information associated with the user A to the node B as a NOTIFY message. The node B receives the presence information, acknowledges the presence of the user A based on the contents thereof, and then initiates or cancels the call connection.
The structure of presence information indicative of the presence of a person is discussed as a presence data model. The data elements of the presence data model are largely divided into three data elements: person, service, and device. The person refers to the data on the user himself/herself, for example, activity information such as being at a meeting or even emotion such as feeling sad. The service means data on communication services such as telephone calls or instant messages and may include, for example, the data on the specification or capability of an image or speech communication scheme. The device is concerned with the data on physical elements such as telephones or personal computers (PC) and may include data such as the availability for communications of whether PCs are running or the remaining level of batteries or the like. As such, the presence of a person can be expressed in the combination of the aforementioned three data elements. For example, one user may be associated with a plurality of nodes when using a telephone and a PC at the same time, in the case of which the presence information of the user can be expressed by any one of these data elements or in combination with these pieces of data.
Conventional Art Literature
Non-Patent Document
Non-Patent Document 1: Gonzalo Camarillo, Miguel A. García Martín “IMS Standard Text.” (translated by Takuya Fukada and Takuya Kashima): RIC TELECOM